Conventional bearing assemblies of this type are well known in the prior art and are used, for example, as wheel hub bearings in motor vehicles. For strength reasons, the bearing rings of the rolling-element bearing are made mostly of steel, rolling-element bearing steel (100Cr6), for example, while a light metal such as aluminum, is used as the material for the hub element or housing element.
Aluminum wheel hubs are weight-saving and therefore advantageous for wheel bearing concepts. However, one disadvantage of aluminum is its substantially greater coefficient of thermal expansion compared to that of steel. This means that it is difficult to design the connection between steel parts and aluminum parts for all relevant temperature ranges. The different coefficients of thermal expansion have an especially negative impact in the compression force of the press-fit between the hub and bearing outer ring. At high temperatures the compression force can decrease so that the bearing outer ring can turn; as a result the hub or the bearing can be damaged.
At low temperatures, however, the aluminum hub strongly constricts the outer ring, so that high compression stresses occur. This can lead to cracking of the hub.
In compact bearings there is also the fact that with the use of a one-piece bearing outer ring, the influence of temperature on the bearing clearance is significant. The result is a disadvantageously large variation of the bearing clearance with respect to the temperature of the bearing assembly. This disadvantageously influences the service life of the bearing assembly.
Attempts have been made to prevent these problems by using cast iron as the hub material; however, the advantage of low weight is thereby lost.
Then the use of steel rings cast in an aluminum hub was envisaged, whereby the rigidity of the bearing can be increased, so that the influence of the press connection on the clearance is reduced. However, in such a solution it is disadvantageous that the costs increase, since the manufacture is relatively expensive, since additional parts must be made.